1. Field of the Invention
The present invention relates to an electrical connection terminal for a connection hole and an engagement structure of an electronic component including the same, and more particularly to an electrical connection terminal for a connection hole which is inserted through a connection hole, and an engagement structure of an electronic component including the same.
2. Description of the Related Art
An engagement structure of an electronic component with which leads of an electronic component with leads are inserted into (through) through holes of a circuit board with through holes, respectively, to engage the electronic component with leads with the circuit board, for example, is known as conventional one in this technical field. This technique, for example, is described in Japanese Patent Laid-Open No. 2000-299250.
This engagement structure of an electronic component includes a printed-wiring board as a circuit board, and an electronic component which is engaged with the printed-wiring board.
The printed-wiring board has at least one pair of through holes which are formed in parallel at predetermined intervals. The electronic component has leads including claw portions which are inserted through the at least one pair of through holes, respectively.
In order to engage the electronic component with the printed-wiring board by using the structure described above, the engagement of the electronic component with the printed-wiring board is performed in such a way that by using an automatic inserting machine, the electronic component is moved and the leads of the electronic component are inserted through the at least one pair of through holes, respectively, from a surface side (from a component mounting surface side) of the printed-wiring board previously placed on a stage. In this case, when the leads of the electronic component are inserted through the at least one pair of through holes, respectively, the claw portions of the leads are engaged with back surface-side opening peripheries of the through holes, respectively. After that, the claw portions of the leads are soft-soldered to the back surface-side opening peripheries (lands) of the through holes, respectively, thereby mounting the electronic component to the circuit board.
In this sort of engagement structure of an electronic component, normally, as shown in FIG. 6, a guide surface (insertion taper surface) 602 having a predetermined lead insertion angle (taper angle) a is formed in a claw portion 601 of a lead 600. Here, the lead insertion angle α means an angle by which the guide surface 602 is inclined with respect to a lead insertion direction (an angle which a side surface 603 and the guide surface 602 make with each other).
This technique, for example, is described in Japanese Patent Publication No. 05-80793, Japanese Patent Laid-Open Nos. 11-297385, 08-69828 and 2001-133352, and Japanese Utility Model Publication No. 07-22058 in addition to Japanese Patent Laid-Open No. 2000-299250.
However, in the case of the conventional engagement structure of an electronic component (refer to Japanese Patent Laid-Open No. 2000-299250), the lead insertion angle α of the guide surface 6002 in the lead 600 is set as single one. For this reason, the conventional engagement structure of an electronic component involves such a problem that when the lead 600 is inserted into the through hole and is then moved in the lead insertion direction, an amount of deflection of the lead 600 increases in correspondence to a movement distance of the lead 600, and thus a lead insertion force gradually increases for a period of time from start of the insertion of the lead into the through hole to end of the insertion of the lead through the through hole.
For this reason, there has been desired the appearance of an engagement structure of an electronic component which is capable of inserting a lead into a through hole by using a lead insertion force held equal to or smaller than a predetermined value (10N) for a period of time from start of insertion of the lead into the through hole to end of the insertion of the lead through the through hole, thereby engaging an electronic component with a circuit board.